1. Field of the Invention
This invention relates to a cylinder pressure sensor output compensation method for internal combustion engines and more particularly to such a method which, when applied in a system for controlling engine operation on the basis of detected cylinder pressure, enables elimination of output errors caused by, for example, manufacturing variance among pressure sensors.
2. Description of the Prior Art
It is well known to control the operation of an internal combustion engine on the basis of detected cylinder pressure and one such method is disclosed in Japanese Patent Publication No. 46(1971)-3527.
For detection of cylinder pressure, the disclosed method uses pressure sensors disposed in the vicinity of the cylinders and the sensors are required to provide outputs that accurately reflect the absolute pressure during the power stroke. In fact, however, there is always a considerable probability of the output of a sensor including an error component. One reason for this is the variance among such sensors from the time of their manufacture and another is acquired variance (degradation) resulting from cylinder heat and other use environment factors. While it is the general practice to provide pressure sensors used for measurement with water cooling or the like, pressure sensors installed in internal combustion engines are positioned in high-temperature regions, making it difficult to carry out adequate cooling. They are thus apt to produce erroneous outputs.